On Monday, July 1, 1850, the populace of occupied nuevomexico voted overwhelmingly to enter the United States as a state rather than a territory. The Mexican departamento of New Mexico had been seized by the U.S. in 1846 during the Mexican/American war. In the July 1850 referendum, the New Mexico also reaffirmed it’s 1848 decision to not allow slavery in New Mexico, and identified state officers and national representatives to Congress.
However, New Mexico’s decision to request U.S. statehood was nullified before it reached Washington DC. While the new congressional delegation was in route to the capital, news of the compromise of 1850 arrived in New Mexico.
More focused on settling the national slavery question than fulfilling New Mexico’s request, the Compromise admitted California as a free slave state and ignored the results of the July election. Instead, Congress made Utah and New Mexico territories where slavery was allowed. This decision was influenced by Texans who wanted to incorporate New Mexico into Texas, which was a slave state.
The boundary between Texas and Mexico was still amorphous, with Texas claiming land to the east bank of the Rio Grande River. In exchange for relinquishing its claim to eastern New Mexico, Congress gave Texas $10 million. To further keep Texas happy, New Mexico would be neither slave nor free. It and Utah territory would have to vote for or against slavery when they applied for statehood.
If New Mexico had entered the union as a state in 1850, it’s almost certain that it was entered as a non-slave state, dramatically altering the balance between slave and free and potentially catapulting the country into the war that would come just over a decade later.
However, by the time New Mexico did become a state, the slavery issue became a moot point, since New Mexico . It would not do so until 1912. Instead, the Congressionally-established New Mexico Territory government took over in Spring 1851. 20 years would pass before another constitutional convention was called and 66 years would go by before New Mexico would shake off its territorial status and officially become one of the United States.
Sources: Thomas C. Donnelly, The Government Of New Mexico, U of NM Press, Albuquerque, 1953; Bruce Glassrud, African-American History In New Mexico, U of NM Press, Albuquerque, 2013; Calvin A and Susan A Roberts, New Mexico, U of NM Press, Albuquerque, 1988; Hal Stratton and Paul Farley, History, Powers, Responsibility, Office Of The Attorney General, State Of New Mexico, State of New Mexico, 1990